Extinguishing chamber in oil circuit breakers for medium voltages



s. JONASSON" 'ET AL EXTINGUISHING CHAMBER IN OIL CIRCUIT Aug. 9, 1960 2,948,791

BREAKERS FOR MEDIUM VOLTAGES Filed June 5, 1958 M v m .m T o Z mm "mm mm o Jr imp flaw wm w I EXTINGUISHINGCHAMBER 1N OIL CIRCUIT FOR .lVLEDIUM VOLTAGES Sven Jonasson and Walter Pncher, Ludvika, Sweden, as-

signors to Allmanna Svenska Elektriska'Aktiebolaget, Vasteras, Sweden, a'corporation of Sweden Filed June 5, 19-58, Ser. No. 740,131

Claims priority, application Sweden June 6, 1957 '1 Claim. (Cl. 200-150) In aplurality' of circuit breakers hitherto known a rapid'extingui'shi'ng of thebrea'king arc has been achieved I by bringing the circuit breaker into contact with a stream of gas or oil. In oil circuit breakers an oil stream has generally been forced through a slot across the arcing channel or through an annular slot against the center of said channel. The oil stream has then been achieved by a pump piston coupled with the movable contact of the circuit breaker or by a different piston, which was moved by the pressure generated by the are at the breaking gap. It has also been proposed to assemble the breaking gases generated at the breaking gap in a space partly filled with oil and to force oil from this space across an arcing channel, when a slot commencing in this channel and communicating with said oil space is liberated when the movable contact traverses said space.

The present invention concerns an extinguishing chamber for oil circuit breakers in which a piston coupled with the movable contact as well as a differential piston achieving an oil stream against the arc are dispensed with. It is, however, provided with a space closed at the top which in its upper part contains gas and in its lower part oil. Differing from known circuit breakers, the said enclosed space, at its lower part is by wide openings or channels, in permanent communication with a space in which the movable contact of the breaking gap is enclosed. The extinguishing chamber is provided with a. stationary contact arranged in the bottom of a cylinder and with a pin-shaped movable contact which is surrounded by an insulating sleeve, which at its upper end is attached to a cover at the upper part of the cylinder and communicates with an oil magazine and at the lower end is provided with a nozzle, through which the movable contact traverses. It is chiefly characterized in that the sleeve, the cylinder and the cover at the upper part of the cylinder limit an annularily formed space which is closed at the upper end and which communicates with the oil magazine through one or a plurality of openings in the wall of the sleeve or the cylinder. In one form of execution there is an oil container at the upper part of the cylinder and the said annular space communicates with the oil magazine through one or a plurality of openings in the wall of the sleeve. In another form the entire extinguishing chamber is plunged into an oil container, so that the oil reaches a little over the oil level in the oil container. In this case there are suitably one or a plurality of openings in the cylinder, through which the annular space between the cylinder and the sleeve communicates with the oil magazine.

By the invention a very simple circuit breaker is attained, which in spite of its simplicity has better extinguishers properties than most commercial circuit breakers for corresponding voltages. The extinguishing chamber contains only one movable member, i.e. a pinshaped movable contact, and an arc extinguishing gas and oil stream is achieved without using differential pistons or pump pistons coupled to the contact pin. There Patented Aug. 9, 1960 are further no valves for controlling the flow of the extinguishing medium. The properties of the extinguishing chamber can be changed within wide limits by changing the gas volume above the annularily formed oil column between said cylinder and the sleeve surrounding the movable contact.

On the accompanying drawing one form of the invention is shown. Fig. 1 shows a vertical section through an extinguishing chamber and Fig. 2 a section through the extinguishing chamber along the line AA in Fig. 1.

In the figures, 1 designates a cylinder of insulating material and 2 a' bottom rigidly joined with said cylinder and carrying the stationary contact 3 of the breaking gap. The cylinder 1 is at its upper part rigidly joined with a cover 4,which simultaneously forms the bottom in a container 5. The cover 4 is also provided with an annu larily shaped guiding member, 6, in which there are openings 7 and an opening 8. The movable contact 9 of the breaking gap traversing the opening 8 in the guiding member 6 is surrounded by an insulating sleeve 10, which at the upper end is attached to the cover 4 and at the lower end is provided with a nozzle 11, through which the movable contact traverses and which it substantially closes, and with guiding members 12 fixing its position in relation to the cylinder 1. The space 13 between the movable contact 9 and the sleeve 10 communicates through openings 7 in the guiding member 6 with the space 14 in the container 5, which space constitutes the oil magazine. The annularily formed space 15 is at the upper end closed by the cover 4. This space communicates through the openings 16 between the guiding members 12 with the space 17, in which the stationary contact 3 is located, and through the channel 18 in the wall of the sleeve 10, the space 13 and the openings 7 with the space 14, which is partly filled with oil. The space 15 contains in its upper part gas and in its lower part oil. The oil level and thus the gas volume is determined by'the position of the opening 18. The movable contact is by means of a link 19 articulated to a lever 20, which is journalled in the consoles 22 on the housing 5. This lever 20 is by means of the rod 21 articulated to an operating mechanism, not shown on the figures.

The circuit breaker works in the following way. When the movable contact 9 at an interruption leaves the stationary contact 3, an arc generating gas is obtained, which gas forms a bubble around the breaking gap. This gas bubble removes part of the oil from the space 17. The removed oil and possibly part of the generated gas streams through the openings 16 into the space 15 and moves in front of it the annular oil column in the lower part of this space like a piston. The gas in the upper part of the space 15 will then be compressed. When the movable contact 9, on its way upwards, has passed the nozzle 11 in the lower part of the sleeve 10, the gas compressed around the breaking gap will escape through the nozzle and force the oil column in the space 13 to the space 14. The said gas stream through the nozzle extinguishes the arc on one of the first occasions when the stream goes throughzero. When the pressure in the space 17, due to the escape of gas, has decreased under a certain value, the oil column in the space 13 is moved downwards by the gas compressed in the upper part of the space and forces the last remainders of gas as well as a small amount of oil into the space 17. After interruption oil from the space 14 flows through the space 13 to the spaces 17 and 15. The flow of oil to the space 15 continues as long as the gas above the annular oil column can flow out through the opening 18 in the sleeve 10. When the gas can no longer flow out, it is compressed, and the flow of oil will end when ber may be located in an oil tank in such a way that the upper part of the cylinder 1 will be located somewhat below the oil level. In this case the opening 18 is suitably arranged in the wall of the cylinder.

We claim as our invention:

An oil circuit breaker comprising a container with a chamber in the bottom thereof, a cover for the container, a stationary contact arranged inside the said chamber, a cooperating vertically movable contact, an insulating sleeve surrounding said movable contact and attached at its upper part to the cover of the container, an oil magazine, at least one oil opening in the said cover providing communication between the said oil magazine and the interior of the said sleeve, a nozzle which is substantially closed by the movable contact as it approaches the stationary contact, said nozzle being arranged in the lower part of the said sleeve, an annular space being formed by said sleeve and by said container and cover and said space being closed at its top but being in permanent communication with the said chamber at the bottom of the container and in permanent communication with the said oil magazine and an oil opening arranged-in the wall of the said sleeve in spaced relation to the'said cover and serving to determine the level of the oil in the said annular space. 7

References Cited in the file of this patent UNITED STATES PATENTS 2,387,589 Kesselring et a1 Oct. 23', 1945 FOREIGN PATENTS 768,278 France May 14, 1934 471,300 Great Britain Sept. 1, 1937 1,050,715 France Sept. 2', 1953 

